1. Field of the Invention
The present invention relates, in general, to a computer system, and more particularly, to a computer system wherein optical devices such as a CD-ROM drive can be driven even while a power switch of the computer system is turned off.
2. Description of the Related Art
Generally, a portable computer comprises a central processing unit (CPU) having operation and control functions, a storage device such as a hard disk drive and a CD-ROM drive and so on, an inputting device such as a touch pad for inputting a mouse pointing, a video chip for processing a video signal, a sound chip for processing an audio signal, a system body on which a main board provided with chip sets controlling data input/output and exchange between the devices is mounted, and an LCD unit coupled to the system body by a hinge, displaying the video signal supplied from the video chip in the form of images.
With the use of a computer equipped with a CD-ROM drive, a typical example of the optical devices, a user can listen to music that he desires to hear, as if he hears the music through an audio system exclusive of the musical listening.
However, in order to listen to music with the use of the portable computer, a power switch (not shown) is selected and the computer system is booted up, thereby allowing the audio data processed in the sound chip to be outputted as the sound.
In this regard, there has been developed a reproduction system wherein an audio file of a disk inserted into the CD-ROM drive can be reproduced even while the portable computer is not in operation. On this system is mounted a separate CD player IC (integrated circuit). On one lateral plane of the system body are provided an auxiliary power switch for supplying the power to the CD player IC and inputting buttons such as PLAY, STOP, BACK, FORWARD, etc., involved in audio reproduction, for controlling the CD player IC. Here, when an inputting button involved in the audio reproduction is selected, the selected signal is inputted through a pin to input a control signal of the CD player IC.
However, with regard to a portable computer whose volume has been reduced as much as possible, considering its portability, it is not reasonable to separately provide inputting buttons involved in the audio production, in terms of the efficiency in utilizing the space.